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Fuel Delivery issue [message #321089] Tue, 25 July 2017 16:12 Go to previous message
andyg is currently offline  andyg   United States
Messages: 12
Registered: January 2011
Location: Atlanta, GA
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Junior Member
Posted this on Facebook, but want to see if there might be some insight here from folks that don't do FB

Hey GMC brain trust, The Pickle (1975 Palm Beach) is having a what I thought may be a fuel delivery issue. Little background, GMC has been set up as a food truck since 2004, and has been maintained as a working truck since. We are out working 3 to 5 days a week pretty much year round, in city/freeway traffic in the Atlanta area. Had the truck at the Coop in Jan for upgrades and to try to stay ahead of mechanical issues. New tranny, bottom of engine was rebuilt, fuel system was upgraded with new 12v pump on the aux tank, main is on the mechanical pump, rebuilt carb. . Also intake had cracks that were magnafluxed and and crossover plate installed to correct.
About a month ago on the way to an event on the freeway w/out traffic, truck just died, engine stopped getting gas, rpm when to zero. Since Jan had been running on just the main tank/using the mechanical fuel pump. Day wasn't that hot, mid 80s was cruising at 65/70 didn't seem like a vapor lock issue to me, check the engine compartment every seemed fine, would crank but not start. Switched to the aux tank with the 12v pump and it started up, got off the highway sitting in a parking lot at idle the engine was running hot 220ish so I shut it down.to let it cool off.. it was running ok, seemed a bit harder to start and had a bit of miss at idle, but didn't leave me stranded on the road. In the last couple weeks it has been running less well, losing power under load and up hills. I have replaced the mechanical fuel pump, and tank selector valve and the carb filter. Spoke to Jim B about it , he thought it might be the carb, so he sent a fresh one which we've swapped out as well.. Still not running right. Will start and run with aux tank/pump, no gas if set on main/mech pump.
Anybody have any insight, ideas or suggestions. I am leaning toward it being two problems. The issue with the mechanical pump/ and the poor performance. I did get a vacuum gauge on the engine yesterday, 15 or so at ideal, between 10 and 15 in gear and below 10 under load. Jim is thinking there is some sort of vacuum leak. Any ideas are appreciated. Thanks!


Andy Grimes Atlanta, GA "The Pickle" 1975 GMC Palm Beach ultimateculinary.com
 
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